JP5386330B2 - A crucible made of quartz glass whose thickness can be visually judged. - Google Patents
A crucible made of quartz glass whose thickness can be visually judged. Download PDFInfo
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Description
本発明は、石英ガラス製ルツボ、特に、引上げ法によるシリコン単結晶の製造時に発生するルツボ厚みの溶解（減肉）量を、目視により判定可能な石英ガラス製ルツボに関するものである。 The present invention relates to a quartz glass crucible, and more particularly to a quartz glass crucible that can visually determine the amount of melting (thinning) of the crucible thickness that occurs during the production of a silicon single crystal by a pulling method.
今日のＩＴ化社会を支えるエレクトロニクス技術、そこで使用される半導体デバイス等の製造にはシリコンウェーハが欠かせない。このシリコンウェーハの特徴の一つに、酸素析出物、転位、酸素積層欠陥などの微小欠陥がある。これらの微小欠陥は、デバイス・プロセスで発生する重金属汚染を捕獲する有益な効果がある一方、デバイス不良の原因にもなり得る。従って、デバイスの種類あるいは使用されるデバイス・プロセスに応じて、結晶中の酸素濃度は所定の濃度に調整される必要がある。 Silicon wafers are indispensable for the electronics technology that supports today's IT society and for the manufacture of semiconductor devices used there. One of the features of this silicon wafer is microdefects such as oxygen precipitates, dislocations, and oxygen stacking faults. While these micro defects have the beneficial effect of capturing heavy metal contamination that occurs in the device process, they can also cause device failure. Therefore, the oxygen concentration in the crystal needs to be adjusted to a predetermined concentration according to the type of device or the device process used.
現在、引上げ法による単結晶シリコンの製造方法としては、チョクラルスキー法（Czochralski 以下 ＣＺ法という）と呼ばれる、シリコンの単結晶を引上げる製造方法が一般的である。また、ＣＺ法に強力な磁場をかけるＭＣＺ法(Magneticfield applied ＣＺ 法)と呼ばれるものもある。
ＣＺ法では、一般的に、ＣＺ炉と呼ばれる装置を用いて、金属不純物の濃度が数ｐｐｂ以下（１ｐｐｂ＝１０億分の１）に高純度化された多結晶シリコン塊および抵抗率調整用のホウ素（B）あるいはリン（P）などを充填し、約１４２０℃で溶融する。
ついで、種結晶シリコン棒をシリコン融液の液面につけ、種結晶あるいは石英ガラス製ルツボを回転させて、種結晶を細く（無転位化）してから引き上げると、種結晶と同じ原子配列をした単結晶シリコンのインゴットが得られる。
Currently, as a method for producing single crystal silicon by a pulling method, a method for pulling a single crystal of silicon called Czochralski method (hereinafter referred to as CZ method) is common. There is also a so-called MCZ method (Magneticfield applied CZ method) in which a strong magnetic field is applied to the CZ method.
In the CZ method, generally, using a device called a CZ furnace, the concentration of metal impurities is refined to a few ppb or less (1 ppb = 1 billionth), and the resistivity adjustment is performed. Fill with boron (B) or phosphorus (P) and melt at about 1420 ° C.
Next, when the seed crystal silicon rod was put on the surface of the silicon melt, the seed crystal or the quartz glass crucible was rotated to make the seed crystal thin (no dislocation) and then pulled up, the same atomic arrangement as the seed crystal was obtained. A single crystal silicon ingot is obtained.
上記したように、石英ガラス製ルツボは、シリコンを溶融して単結晶シリコンとして引上げる際に、シリコンの溶融液を溜めておくものである。そして、この引上げ工程の中、石英ガラス製ルツボの内側が溶融シリコン溶解することで、石英ガラス製ルツボ自身の厚みが減少していく（以下、減肉という）現象が起こる。
また、単結晶シリコン中の酸素濃度は、例えば、Ｐ型太陽電池用のシリコン単結晶ウェーハの場合、ウェーハ中の酸素濃度と光電変換効率との間には相関があり、光電変換効率を維持するためには、ウェーハ中の酸素濃度を制御しなければならない。
ここで、単結晶シリコン中の酸素濃度は、石英ガラス製ルツボから供給される酸素量に強く依存するため、この石英ガラス製ルツボの溶解という現象は重要となってくる。しかしながら、溶け込む酸素量自身を、直接、定量的に把握することは今のところできない。
そこで、現在では、石英ガラス製ルツボの厚みの減肉量を溶融シリコンに供給される酸素量の指標としているが、結局のところ、このルツボの減肉量も、ＣＺ炉外から直接測定することができないために減肉量の判定は製造中の経験則に頼るしか手段がなかった。
さらに、近年、シリコンウェーハ上のデバイス集積度が上がっているため、求められる酸素濃度の許容範囲はますます狭くなる傾向にあり、上述したような経験的な調整のみで上記した許容範囲内を満足するように、ウェーハ中の酸素濃度を制御することはとても難しくなってきている。
As described above, the quartz glass crucible is for storing a silicon melt when the silicon is melted and pulled up as single crystal silicon. During the pulling process, the inside of the quartz glass crucible is melted with molten silicon, thereby causing a phenomenon in which the thickness of the quartz glass crucible itself decreases (hereinafter referred to as thinning).
Further, the oxygen concentration in the single crystal silicon, for example, in the case of a silicon single crystal wafer for P-type solar cells, there is a correlation between the oxygen concentration in the wafer and the photoelectric conversion efficiency, and the photoelectric conversion efficiency is maintained. In order to do this, the oxygen concentration in the wafer must be controlled.
Here, since the oxygen concentration in the single crystal silicon strongly depends on the amount of oxygen supplied from the quartz glass crucible, the phenomenon of melting the quartz glass crucible becomes important. However, it is currently impossible to quantitatively grasp the amount of dissolved oxygen itself.
Therefore, at present, the thickness reduction of the quartz glass crucible is used as an indicator of the amount of oxygen supplied to the molten silicon, but in the end, the thickness reduction of the crucible should be measured directly from outside the CZ furnace. Therefore, the only way to determine the amount of thinning is to rely on empirical rules during production.
Furthermore, as the degree of device integration on silicon wafers has increased in recent years, the required oxygen concentration tolerance has tended to become narrower, and the above-mentioned tolerance has been satisfied only by empirical adjustment as described above. Thus, it has become very difficult to control the oxygen concentration in the wafer.
また、石英ガラス製ルツボ自身の減肉は、その程度が進むと、溶融シリコンの重みを石英ガラス製ルツボ自身で保持することができずに、穴が開きやすくなるという問題が発生する。そして、一旦、ルツボ壁に孔が開くと、ルツボ中の高温のシリコンの溶融液が石英ガラス製ルツボ外に漏れ出し、設備に重大な損傷を与えるのみならず、最悪の場合、設備の冷却水と接して、水蒸気爆発を誘発するおそれすらある。
特に、近年、その需要が増えてきた一つの石英ガラス製ルツボで複数本の単結晶シリコンを同時に引上げる、いわゆるマルチ引き上げという引上げ方法を行った場合には、従来よりも引き上げ時間が長く必要となり、それに従って、石英ガラス製ルツボの減肉量も大きくなる。すなわち、単結晶シリコンの引上げ中に、ＣＺ炉外から直接的に石英ガラス製ルツボの厚みを把握して、上記した危機を回避することは、酸素濃度の制御等の単結晶シリコンの製品品質上有効であるだけでなく、単結晶シリコン引上げの製造工程の安全性を確保する上でとても重要である。
Further, when the thickness of the quartz glass crucible itself is reduced, the weight of the molten silicon cannot be held by the quartz glass crucible itself, which causes a problem that holes are easily opened. Once a hole is opened in the crucible wall, the high-temperature silicon melt in the crucible leaks out of the quartz glass crucible and causes serious damage to the equipment. There is even the possibility of inducing a steam explosion in contact with.
In particular, when a pulling method called so-called multi-pulling, in which a single quartz silicon crucible, which has been in increasing demand in recent years, pulls up multiple single crystal silicons at the same time, is required to take longer than before. Accordingly, the thickness reduction of the quartz glass crucible also increases. In other words, to avoid the above-mentioned crisis by grasping the thickness of the quartz glass crucible directly from the outside of the CZ furnace during the pulling of the single crystal silicon, the product quality of the single crystal silicon such as the control of the oxygen concentration Not only is it effective, it is very important in ensuring the safety of the manufacturing process for pulling single crystal silicon.
近年では、単結晶シリコンインゴットの大口径化（直径：300mm以上）が進み、石英ガラス製ルツボの中の溶融シリコンの質量が、ますます増える傾向（200kg以上）にある。ここで、単結晶シリコンインゴットの大口径化が進むと、単結晶シリコンの引上げの際に溶融シリコンの液面（以下、湯面という）が波立つ現象（以下、波立ちという）が現れる。
この波立ちを防止するために、例えば、特許文献１に記載のような、気泡の含有を調整した、波立ちを防止用の特殊層が設けられる場合がある。しかし、石英ガラス製ルツボが溶融シリコンに溶解するので、この特殊層もその溶解に伴って厚みが減少し、やはり減肉化する。
この特殊層が溶解により完全に消失してしまうと、溶融シリコンの湯面は波立ちやすくなり、その結果、シリコン単結晶に転位が入りはじめ、それがひどくなると、単結晶シリコンの引上げ自体を停止する事態にもなる。従って、シリコン単結晶の引上げに際しては、特殊層の厚みの残量を事前に把握するといった点からも、ＣＺ炉外から直接的に石英ガラス製ルツボの減肉量を把握する重要性はますます高まっている。
In recent years, the diameter of single crystal silicon ingots has increased (diameter: 300 mm or more), and the mass of molten silicon in a quartz glass crucible tends to increase (200 kg or more). Here, when the diameter of the single crystal silicon ingot is increased, a phenomenon (hereinafter referred to as undulation) that the liquid level of molten silicon (hereinafter referred to as the molten metal surface) undulates when the single crystal silicon is pulled up.
In order to prevent this undulation, for example, a special layer for preventing undulation may be provided as described in Patent Document 1 in which the inclusion of bubbles is adjusted. However, since the quartz glass crucible dissolves in the molten silicon, the thickness of the special layer also decreases with the dissolution, and the thickness is reduced.
When this special layer disappears completely by melting, the molten silicon melt surface becomes prone to ripples. As a result, dislocations begin to enter the silicon single crystal, and when it becomes severe, the pulling of the single crystal silicon itself stops. It also happens. Therefore, when pulling up the silicon single crystal, it is more important to know the amount of thinning of the quartz glass crucible directly from outside the CZ furnace, from the standpoint of knowing the remaining thickness of the special layer in advance. It is growing.
石英ガラス製ルツボの減肉による事故の防止策として、特許文献２では、シリコンの溶融液が石英ガラス製ルツボ外に漏れ出した場合の受け皿の設置を提案している。
また、特許文献３では、石英ガラス製ルツボと黒鉛製のルツボの間に黒鉛保護シートを挿入することが提案されている。
As a measure for preventing an accident due to thinning of the quartz glass crucible, Patent Document 2 proposes installation of a saucer when a silicon melt leaks out of the quartz glass crucible.
Patent Document 3 proposes inserting a graphite protective sheet between a quartz glass crucible and a graphite crucible.
しかしながら、特許文献２および３に開示の技術はいずれも、石英ガラス製ルツボが破損した場合の二次的な対応策であり、最も重要な、単結晶シリコン引上げ中の石英ガラス製ルツボの減肉量を、ＣＺ炉外から直接的に判定する技術には至っていない。
すなわち、依然として、シリコン単結晶の引上げ中に、石英ガラス製ルツボの減肉量の正確な判定ができないという問題が残っていた。
However, both of the techniques disclosed in Patent Documents 2 and 3 are secondary countermeasures when the quartz glass crucible is broken, and most importantly, the thinning of the quartz glass crucible during pulling of the single crystal silicon. A technique for directly determining the amount from outside the CZ furnace has not been reached.
That is, there still remains a problem that it is impossible to accurately determine the thickness reduction of the quartz glass crucible during the pulling of the silicon single crystal.
本発明は、上述した問題を有利に解決するもので、シリコン単結晶の引上げ中に、石英ガラス製ルツボにおける減肉量の判定を、ＣＺ炉外から直接的に容易かつ正確に実施できる石英ガラス製ルツボを提供することを目的とする。また、特殊層を設けた石英ガラス製ルツボの場合は、その特殊層の残厚みを簡単に把握し、管理することのできる石英ガラス製ルツボを提供することを目的とする。 The present invention advantageously solves the above-described problem, and enables quartz glass crucibles to be easily and accurately determined directly from the outside of a CZ furnace while pulling up a silicon single crystal. The purpose is to provide a crucible. In addition, in the case of a quartz glass crucible provided with a special layer, an object is to provide a quartz glass crucible that can easily grasp and manage the remaining thickness of the special layer.
すなわち、本発明の要旨構成は次のとおりである。
（１）上面に開口した端部を有する円筒状の直胴部と、すり鉢状の底部と、それらを連接するコーナー部とを備え、シリコン単結晶を引き上げる炉の中に配置して使用する石英ガラス製ルツボであって、少なくとも上記直胴部の内壁面の水平線上、１箇所または２箇所以上に深さが異なる窪み群からなる凹部を、前記炉の外から目視で確認したときに、いずれか１つの凹部が確認できる間隔を開けて設けたことを特徴とする減肉量が目視判定可能な石英ガラス製ルツボ。
That is, the gist configuration of the present invention is as follows.
(1) a cylindrical straight barrel having an open end on the top surface, a cone-shaped bottom, and a corner portion which connects them to use by placing in a furnace pulling a silicon single crystal A crucible made of quartz glass, at least on the horizontal line of the inner wall surface of the straight body part, when a concave part consisting of a group of depressions having different depths at one place or two places or more is visually confirmed from the outside of the furnace, A quartz glass crucible capable of visually determining the amount of thinning, characterized in that it is provided with an interval at which any one recess can be confirmed .
（２）前記凹部の幅は、１〜500μmとすることを特徴とする前記（１）に記載の減肉量が目視判定可能な石英ガラス製ルツボ。 (2) The quartz glass crucible according to (1), wherein the thickness of the concave portion is 1 to 500 μm, and the thickness reduction amount can be visually determined.
（３）前記凹部の深さは、１μm以上とすることを特徴とする前記（１）または（２）に記載の減肉量が目視判定可能な石英ガラス製ルツボ。 (3) The quartz glass crucible according to (1) or (2), wherein the depth of the concave portion is 1 μm or more, and the amount of thinning can be visually determined.
（４）前記凹部の深さは、前記ルツボの厚みの0.05〜50％とすることを特徴とする前記（１）〜（３）いずれかに記載の減肉量が目視判定可能な石英ガラス製ルツボ。 (4) The depth of the concave portion is 0.05 to 50% of the thickness of the crucible. The thickness reduction amount according to any one of (1) to (3) is made of quartz glass that can be visually determined. Crucible.
（５）前記凹部の幅と深さの比（幅／深さ）は、0.8以下とすることを特徴とする前記（１）〜（４）いずれかに記載の減肉量が目視判定可能な石英ガラス製ルツボ。 (5) The ratio (width / depth) between the width and the depth of the recess is 0.8 or less, and the thickness reduction amount according to any one of (1) to (4) can be visually determined. A quartz glass crucible.
（６）前記（１）〜（５）において、水平線上の凹部領域をルツボの縦方向に多段に設
けたことを特徴とする前記（１）〜（５）いずれかに記載の減肉量が目視判定可能な石英
ガラス製ルツボ。
(6) In said (1)- (5) , the recessed part on a horizontal line was provided in multiple stages in the vertical direction of the crucible, The thickness reduction amount in any one of said (1)- (5) characterized by the above-mentioned. A quartz glass crucible that can be visually judged.
（７）前記凹部領域が、直胴部に配置されていることを特徴とする前記（１）〜（６）いずれかに記載の減肉量が目視判定可能な石英ガラス製ルツボ。
(7) The crucible glass crucible according to any one of the above (1) to (6), wherein the thickness reduction is visually determined, wherein the concave region is disposed in a straight body portion.
本発明によれば、シリコン単結晶の引上げ中に、石英ガラス製ルツボにおける減肉量を、ＣＺ炉外からでも容易かつ正確に判定することができ、その結果、安全で安定したシリコン単結晶の引上げが可能となる。 According to the present invention, it is possible to easily and accurately determine the thinning amount in the quartz glass crucible even from the outside of the CZ furnace during the pulling of the silicon single crystal. As a result, the safe and stable silicon single crystal Pulling up is possible.
以下、本発明を具体的に説明する。
本発明に用いる凹部を設ける前の石英ガラス製ルツボは、ＣＺ法などを行う際に、シリコンを溶融して単結晶のインゴットとして引上げるために、シリコンの溶融液を溜めておく石英ガラス製ルツボであるが、そのルツボに対し特段の限定はなく、従来公知のものいずれもが適用できる。
Hereinafter, the present invention will be specifically described.
The quartz glass crucible before the formation of the concave portion used in the present invention is a quartz glass crucible for storing a silicon melt to melt silicon and pull it up as a single crystal ingot when performing the CZ method or the like. However, the crucible is not particularly limited, and any conventionally known crucible can be applied.
本発明では、上記した石英ガラス製ルツボの内壁面の水平線上、１箇所または２箇所以上に凹部を設けるところに特徴がある。図１に、本発明に従う凹部の形状を示した石英ガラス製ルツボの横断面図を示す。図中、１は石英ガラス製ルツボ、２は凹部、３は窪み群、3aは孔である。
この凹部は、例えば、図１(a)に示すように、判定する減肉の程度によって、予め設定した深さを有する１または２個以上の凹部を、内壁面の水平線上の１箇所または２箇所以上に設ける。
The present invention is characterized in that a concave portion is provided at one or two or more locations on the horizontal line of the inner wall surface of the quartz glass crucible described above. FIG. 1 shows a cross-sectional view of a quartz glass crucible showing the shape of a recess according to the present invention. In the figure, 1 is a crucible made of quartz glass, 2 is a recess, 3 is a recess group, and 3a is a hole.
For example, as shown in FIG. 1 (a), this recess is formed by replacing one or more recesses having a preset depth with one or two horizontal lines on the inner wall surface, depending on the degree of thinning to be determined. Provide more than one place.
上記したような凹部を設けることによって、凹部が１箇所の場合は、この凹部が消えた時点で、その凹部深さに石英ガラス製ルツボの減肉量が達していることが分かる。また、２箇所以上に、深さの異なる凹部を設けた場合には、石英ガラス製ルツボの内壁面の減肉量を、それぞれの凹部の消失時点によって推定することができる。 By providing the recesses as described above, it can be seen that when the number of recesses is one, the thickness of the quartz glass crucible reaches the depth of the recess when the recess disappears. Moreover, when the recessed part from which a depth differs is provided in two or more places, the thinning amount of the inner wall surface of the crucible made from quartz glass can be estimated by the time of disappearance of each recessed part.
上記の本発明における凹部の幅（または外径）は、１〜500μmの範囲とすることが望ましい。というのは、１μmに満たないと、消失の様子を観察することが難しく、一方500μmを超えると、凹部の底の減肉が始まり、凹部自身の深さが変わるおそれがでてくるからである。好ましくは、50〜200μmの範囲である。 The width (or outer diameter) of the recess in the present invention is preferably in the range of 1 to 500 μm. This is because if it is less than 1 μm, it is difficult to observe the disappearance, whereas if it exceeds 500 μm, the thickness of the bottom of the recess starts to decrease, and the depth of the recess itself may change. . Preferably, it is the range of 50-200 micrometers.
また、凹部の深さは、石英ガラス製ルツボの厚みや、その使用状況、減肉量の程度等に基づいて設定できるが、1μm以上とすることが望ましい。または前記ルツボの厚みの0.05％以上であって前記ルツボの厚みの50％以下の範囲とすることが望ましい。
というのは、凹部の深さがルツボの厚みの1μmに満たない、またはルツボの厚みの0.05％に満たないと、凹部の消失が速すぎて、正確に減肉を判定できないおそれがあり、一方、凹部の深さがルツボの厚みの50％を超えると、その部分が、石英ガラス製ルツボの欠陥として作用するおそれが出てくるからである。
Further, the depth of the recess can be set based on the thickness of the quartz glass crucible, the use state thereof, the degree of thickness reduction, etc., but is preferably 1 μm or more. Alternatively, it is desirable that the thickness be 0.05% or more of the crucible thickness and 50% or less of the crucible thickness.
This is because if the depth of the recess is less than 1 μm of the thickness of the crucible, or less than 0.05% of the thickness of the crucible, the disappearance of the recess may be too fast to accurately determine the thinning, This is because if the depth of the concave portion exceeds 50% of the thickness of the crucible, the portion may act as a defect of the quartz glass crucible.
さらに、凹部の幅と深さの比（幅／深さ）は、0.8以下の範囲とすることが望ましい。というのは、凹部の底が減肉することを抑制するには、
界面反応：SiO2（固）→Si(液）＋２Oの制御が必要で、その手段としては、Si-SiO2界面におけるシリコン融液中の酸素濃度を高くすることが考えられる。ここで、酸素濃度を高くする手段としては、酸素の拡散を抑制すれば良いが、拡散に最も影響を与えるのは、シリコン融液の熱対流の影響であるため、熱対流を抑制すれば良い。すなわち、凹部の幅と深さの比（幅／深さ）を0.8以下に制限すると、容易に熱対流の影響を抑制することができるため望ましい。なお、上記の凹部の幅と深さの比の制限は、特に、凹部の幅が、200μmを超えた場合に有効である。
Furthermore, it is desirable that the ratio between the width and the depth of the recess (width / depth) is 0.8 or less. Because to suppress the thickness of the bottom of the recess,
Interfacial reaction: It is necessary to control SiO 2 (solid) → Si (liquid) + 2O. As a means for this, it is conceivable to increase the oxygen concentration in the silicon melt at the Si—SiO 2 interface. Here, as a means for increasing the oxygen concentration, it is only necessary to suppress the diffusion of oxygen. However, since it is the influence of the thermal convection of the silicon melt that most affects the diffusion, it is only necessary to suppress the thermal convection. . That is, it is desirable to limit the ratio of the width and depth of the recess (width / depth) to 0.8 or less because the influence of thermal convection can be easily suppressed. The above limitation on the ratio of the width and depth of the recess is particularly effective when the width of the recess exceeds 200 μm.
本発明では、上記した水平線上の１箇所または２箇所以上に設ける凹部を、図１(b)に示すような、いくつかの深さの異なる孔、すなわち窪み群とすることもできる。この際、窪み群の最大の孔深さは、100μm以上とすることが好ましい。また、これら群の間隔は、凹部の最大深さ以上とするのが好ましい。
この場合は、深さの異なる孔の消え方によって、石英ガラス製ルツボの減肉量をより正確に判定することができる。
In the present invention, the concave portions provided at one place or two places or more on the horizontal line described above can be formed as several holes having different depths, that is, depression groups, as shown in FIG. At this time, it is preferable that the maximum hole depth of the depression group is 100 μm or more. Moreover, it is preferable that the space | interval of these groups shall be more than the maximum depth of a recessed part.
In this case, the thickness reduction of the quartz glass crucible can be more accurately determined by the disappearance of the holes having different depths.
また、実際に、ＣＺ法に石英ガラス製ルツボを供し、減肉量を観察する予察試験を行った結果を用いて、前述した凹部の深さ、個数および形状等を設定することは、より効果的な凹部の設定を可能とする。
上記した凹部を設ける領域は、いずれも同一水平線上に複数箇所、施すこともできるし、石英ガラス製ルツボの高さ（縦）方向に、いくつかの群を、多段に配置することもできる。
なお、本発明における凹部の形状は、その消失がＣＺ法等の炉外から確認できるものであれば、特に制限はないが、円形や、三角形、四角形などの断面が例示され、孔、細孔またはスリット等も例示できる。
また、本発明において、凹部の幅とは、上記断面形状の外径や対角線等、その形状の中で、最も長い直線部分の長さを指す。
In addition, it is more effective to set the depth, number, shape, etc. of the recesses described above using the results of a preliminary test in which a quartz glass crucible is applied to the CZ method and the amount of thinning is observed. It is possible to set a specific recess.
A plurality of the regions where the recesses are provided can be provided on the same horizontal line, or several groups can be arranged in multiple stages in the height (vertical) direction of the quartz glass crucible.
The shape of the recess in the present invention is not particularly limited as long as the disappearance can be confirmed from the outside of the furnace such as the CZ method. Or a slit etc. can be illustrated.
In the present invention, the width of the concave portion refers to the length of the longest straight line portion in the shape, such as the outer diameter or diagonal line of the cross-sectional shape.
さらに、本発明に従う凹部は、前述したような溶融シリコンの湯面の波立ちを防止するための特殊層を石英ガラス製ルツボに設けている場合、石英ガラス製ルツボ使用時における特殊層の残量を確認する指標として使用することができる。 Furthermore, when the concave portion according to the present invention is provided with a special layer for preventing the molten silicon melt surface as described above in the quartz glass crucible, the remaining amount of the special layer when the quartz glass crucible is used. It can be used as an indicator to check.
図２に、上面に開口した縁部を有する円筒状の直胴部と、すり鉢状の底部と、それらを連接するコーナー部とを備える石英ガラス製ルツボの、底部の中心を通る縦断面図を示す。図中、１は石英ガラス製ルツボ、２は凹部、４はルツボの開口縁部（リム部）、５はルツボのコーナー部、６がルツボの直胴部、そして、７がルツボの底部であり、本発明では、同図に示したように凹部２をこの直胴部６の内壁に設ける。
特に、本発明おいて凹部を設ける位置は、石英ガラス製ルツボの開口縁部４の５〜200mm程度下方からコーナー部５の上方０〜100mm程度の範囲の直胴部６の内壁に施すことが好ましい。というのは、この範囲に溶融シリコンの湯面が最も長時間存在しており、減肉量の正確な判定を必要とするところだからである。
なお、上記した窪みは、その使用状態によっては、図２に示すコーナー部に設けることを妨げるものではない。
FIG. 2 is a longitudinal sectional view passing through the center of the bottom of a quartz glass crucible having a cylindrical straight body having an edge opened on the upper surface, a mortar-shaped bottom, and a corner connecting the mortar. Show. In the figure, 1 is a quartz glass crucible, 2 is a recess, 4 is an opening edge (rim) of the crucible, 5 is a corner of the crucible, 6 is a straight body of the crucible, and 7 is a bottom of the crucible. In the present invention, the recess 2 is provided on the inner wall of the
In particular, in the present invention, the concave portion is provided on the inner wall of the
In addition, depending on the use state, the above-described depression does not prevent the depression from being provided in the corner portion shown in FIG.
図２に示した断面図のように、石英ガラス製ルツボは、曲率が比較的大きいコーナー部５と、上面に開口した縁部を有する円筒状の直胴部６と、直線または曲率が比較的小さい曲線からなる底部７とを有している。なお、本発明において、コーナー部５とは、直胴部６および底部７を連接する部分で、コーナー部５の曲線の接線が石英ガラス製ルツボの直胴部６と重なる点から、底部７と共通接線を有する点までの部分のことを意味する。
As shown in the cross-sectional view of FIG. 2, the quartz glass crucible has a
また、凹部を形成する方法については特に制限はなく、石英ガラス製ルツボに前記したような凹部を付けられるものであれば、従来公知の方法がいずれも好適に適用できる。
なお、凹部の深さ程度によって、その形成方法は選択されるが、中でも、炭酸ガスレーザーで窪みを形成することが好ましい。というのは、本発明でも重要な、窪みの深さを正確に制御することができるからである。
Moreover, there is no restriction | limiting in particular about the method of forming a recessed part, As long as the above-mentioned recessed part can be attached to the crucible made from quartz glass, all the conventionally well-known methods can be applied suitably.
In addition, although the formation method is selected according to the depth degree of a recessed part, it is preferable to form a hollow with a carbon dioxide gas laser especially. This is because the depth of the depression, which is important in the present invention, can be accurately controlled.
炭酸ガスレーザーの好適な照射条件は以下のとおりである。
発振波長帯域 ：10.6μｍ
最大出力エネルギー ：10Ｊ
ビーム拡がり角 ：0.5mrad
繰り返し ：single, 0-12Hz
パルス幅 ：180ｎs
ジッタ− ：±60ns
スイッチング方式 ：半導体スイッチ方式
レーザ装置寸法 ：W83cm×H60cm×D271cm
Suitable irradiation conditions of the carbon dioxide laser are as follows.
Oscillation wavelength band: 10.6μm
Maximum output energy: 10J
Beam divergence angle: 0.5mrad
Repeat: single, 0-12Hz
Pulse width: 180ns
Jitter: ± 60ns
Switching method: Semiconductor switch method
Laser equipment dimensions: W83cm x H60cm x D271cm
本発明において、例えば、ＣＺ炉に専用の観察窓を設けることで、凹部がシリコン融液より上に来た場合、石英表面の温度が低くなるので目視で見ることができる。また、目視で見えにくい場合でも、光量調整用の偏向板と熱対策用のハーフミラー（入射した光の 一部は反射し、一部は透過する）を設けてカメラ等で観察すれば確認することができる。
なお、ＣＺ炉は従来公知の炉いずれもが好適に使用でき、また、本発明の目視判定とは、直接視認だけでなく、従来公知の視認補助手段、例えば、上記の偏向板や、カメラによる画像、写真等の視認による判定も含むものとする。
In the present invention, for example, by providing a dedicated observation window in the CZ furnace, when the recess comes above the silicon melt, the temperature of the quartz surface is lowered, so that it can be visually observed. In addition, even if it is difficult to see visually, it can be confirmed by observing with a camera etc. with a deflector for adjusting the light quantity and a half mirror for heat countermeasures (part of the incident light is reflected and part is transmitted) be able to.
In addition, any conventionally known furnace can be suitably used as the CZ furnace, and the visual judgment of the present invention is not limited to direct visual recognition, but by a conventionally known visual aid means such as the above-described deflecting plate or camera. It also includes determination by visual recognition of images, photographs, and the like.
従来公知の方法で製造され、天然石英を主成分（天然石英／合成石英＝2/1）とする特殊層を、幅：30mm、厚さ：100μmで有する石英ガラス製ルツボ（口径：800mm、肉厚：70mm）に、以下に示す手順で、本発明に従う凹部を施した。なお、凹部の大きさは、直径：50μm、深さが、５，10，30，65，100μmの５種類の円筒状の孔を作製した。 A quartz glass crucible (caliber: 800 mm, meat, manufactured by a conventionally known method and having a special layer mainly composed of natural quartz (natural quartz / synthetic quartz = 2/1) with a width of 30 mm and a thickness of 100 μm) Thickness: 70 mm) was provided with a recess according to the present invention by the following procedure. Note that five types of cylindrical holes having a diameter of 50 μm and a depth of 5, 10, 30, 65, and 100 μm were prepared.
〔レーザーマーキング手順〕
1.ルツボの芯出し用の中心部にレーザー加工機用の開口部がある敷板に石英ガラス製ルツボの開口部を下にした状態で乗せる工程、
2.３爪スクロールチャック機構による石英ガラス製ルツボの芯出し工程、
3.石英ガラス製ルツボの内壁面側にレーザー加工機が昇降する工程、
4.レーザー装置に内臓された波長：650nmの赤色半導体レーザーにより、石英ガラス製ルツボ内壁面−レーザー照射口の距離を調整する工程、
5.レーザーにより凹部を設ける工程、
6.サーボ制御機構を持つ敷板が回転し、順次凹部マーキングを繰り返す工程、
7.レーザー加工機が原点位置に戻る工程
[Laser marking procedure]
1. A process of placing a quartz glass crucible opening down on a base plate having a laser processing machine opening in the center for crucible centering,
2.3 Centering process of quartz glass crucible by 3-jaw scroll chuck mechanism,
3. The process of raising and lowering the laser processing machine on the inner wall side of the quartz glass crucible,
4. The process of adjusting the distance between the quartz glass crucible inner wall surface and the laser irradiation port using a red semiconductor laser with a wavelength of 650 nm built in the laser device,
5. The process of forming the recess by laser,
6. The process of rotating the base plate with servo control mechanism and sequentially repeating the concave marking,
7. The process of returning the laser processing machine to the origin position
ここに、炭酸ガスレーザーの照射条件は以下のとおりである。
発振波長帯域 ：10.6 μｍ
最大出力エネルギー ：10 Ｊ
ビーム拡がり角 ：0.5 mrad
繰り返し ：single, 0-12 Hz
パルス幅 ：180 ｎs
ジッタ− ：±60 ns
スイッチング方式 ：半導体スイッチ方式
レーザ装置寸法 ：W83 cm×H60 cm×D271 cm
The carbon dioxide laser irradiation conditions are as follows.
Oscillation wavelength band: 10.6 μm
Maximum output energy: 10 J
Beam divergence angle: 0.5 mrad
Repeat: single, 0-12 Hz
Pulse width: 180 ns
Jitter: ± 60 ns
Switching method: Semiconductor switch method
Laser equipment dimensions: W83 cm x H60 cm x D271 cm
石英ガラス製ルツボに、直径：50μmの丸孔タイプの凹部の窪み群（深さは５，10，30，65，100μm）を複数箇所設けている。
また、上記した窪み群は、高さ方向で、開口縁部から50，200，300mmのところに設けている。
A quartz glass crucible is provided with a plurality of recesses (depths of 5, 10, 30, 65, 100 μm) of round hole type recesses having a diameter of 50 μm.
Further, the above-described dent group is provided at 50, 200, and 300 mm from the opening edge in the height direction.
ついで、上記した石英ガラス製ルツボを用い、これに多結晶シリコン塊を入れ、6.67kPaの圧力のアルゴンガス雰囲気中において、室温(20℃)から1500℃までを10時間で昇温した後、1500℃にて所定時間保持し、上記シリコン塊を溶融してシリコン融液とした。この時、上記の凹部は、全てシリコン融液に没して見えなくなっていた。
このシリコン融液に種結晶を浸し、ネッキングを形成した後、石英ガラス製ルツボを回転しながら徐々に引上げてシリコン単結晶を成長させた。この時の石英ガラス製ルツボの内壁面の侵食速度は15μm／ｈを目標として、シリコン単結晶の引上げ条件を設定した。
Next, using the above-described quartz glass crucible, a polycrystalline silicon lump was put into this, and after raising the temperature from room temperature (20 ° C.) to 1500 ° C. in 10 hours in an argon gas atmosphere at a pressure of 6.67 kPa, 1500 The silicon lump was melted for a predetermined time at a temperature to obtain a silicon melt. At this time, the above-mentioned concave portions were all immersed in the silicon melt and disappeared.
After seed crystals were immersed in this silicon melt to form necking, a quartz single crystal was grown by gradually pulling up while rotating a quartz glass crucible. The pulling conditions for the silicon single crystal were set so that the erosion rate of the inner wall surface of the quartz glass crucible at this time was 15 μm / h.
上記シリコン単結晶を引上げながら、上記石英ガラス製ルツボをＣＺ炉の外から目視で確認した。引上げ開始から2時間後、１箇所の窪み群が見え始めたが、前記した凹部の内、深さ：５μmの孔および深さ：10μmの孔は消失していた。また、深さ：30，65，100μmの孔は、消失していなかったが、30μmの孔はかなり浅くなっているのが観察された。
引上げ開始から４時間後、２箇所目の窪み群が見え始めたが、前記した凹部の内、深さ：５，10，30μmの孔は消失していた。また、深さ：65，100μmの孔は、消失していなかったが、65μmの孔はかなり浅くなっているのが観察された。
While pulling up the silicon single crystal, the quartz glass crucible was visually confirmed from the outside of the CZ furnace. Two hours after the start of the pulling, one dent group started to appear, but the hole of depth: 5 μm and the hole of depth: 10 μm had disappeared in the above-mentioned recess. In addition, the pores with depths of 30, 65 and 100 μm did not disappear, but the pores with a depth of 30 μm were observed to be considerably shallow.
Four hours after the start of the pulling, the second dent group started to appear, but the holes with depths of 5, 10, and 30 μm disappeared from the above-described recesses. Moreover, although the hole of depth: 65,100 micrometers was not lose | disappeared, it was observed that the hole of 65 micrometers is considerably shallow.
上記単結晶シリコン引上げの実験終了後、上記石英ガラス製ルツボの肉厚減少量を、２時間後に観察されたところの近傍の断面を切出し、SEM（走査型電子顕微鏡）で拡大して詳細に計測したところ、凹部近傍で、21μm程度の減肉が認められ、上記した特殊層の残量は79μmであった。同じく、４時間後に観察されたところの近傍の断面を切出し、SEM（走査型電子顕微鏡）で拡大して詳細に計測したところ、凹部近傍で、40μm程度の減肉が認められ、上記した特殊層の残量は60μmであった。
なお、上記した消失していない孔の残量（深さ）を測定したところ、孔深さに変化がなく、減肉量の管理孔としての有効性を確認した。
After the experiment of pulling up the single crystal silicon, the thickness reduction of the quartz glass crucible was measured in detail by cutting out the cross section near where it was observed after 2 hours and expanding it with a scanning electron microscope (SEM). As a result, thinning of about 21 μm was observed in the vicinity of the recess, and the remaining amount of the special layer was 79 μm. Similarly, when a cross section near the portion observed after 4 hours was cut out and enlarged with a scanning electron microscope (SEM) and measured in detail, a thinning of about 40 μm was observed in the vicinity of the recess. The remaining amount of was 60 μm.
In addition, when the residual amount (depth) of the above-mentioned non-disappearing hole was measured, there was no change in the hole depth, and the effectiveness of the thinning amount as a management hole was confirmed.
以上の結果から、本発明に従う凹部によって、単結晶シリコン引き上げ中に、正確に石英ガラス製ルツボの減肉量を管理すると共に、波立ち防止用の特殊層の残存厚みの管理、さらには単結晶シリコン引上げ時の石英ガラス製ルツボの侵食速度の設定値を確認することもできることが分かった。 From the above results, the concave portion according to the present invention accurately manages the thinning amount of the quartz glass crucible during pulling of the single crystal silicon, manages the remaining thickness of the special layer for preventing undulations, and further single crystal silicon. It was found that the set value of the erosion rate of the quartz glass crucible during pulling can be confirmed.
本発明は、ＣＺ法等による単結晶シリコンの引上げ製造時に溶融シリコンを溜めておく石英ガラス製ルツボの減肉量を正確かつ容易に判定することによって、溶融シリコンの波立ちを効果的に抑えられるために、転位の少ない高品位シリコン単結晶インゴットの製造でき、かつルツボの穴あきを防止することできるため、安全に製造を行うことができる。 In the present invention, it is possible to effectively suppress the undulation of molten silicon by accurately and easily determining the thickness reduction of a quartz glass crucible that stores molten silicon when pulling up single crystal silicon by the CZ method or the like. In addition, a high-quality silicon single crystal ingot with few dislocations can be manufactured, and the crucible can be prevented from being drilled, so that it can be manufactured safely.
１ 石英ガラス製ルツボ
２ 凹部
３ 窪み群
3a 孔
４ 開口縁部
５ コーナー部
６ 直胴部
７ 底部
1 Crucible made of quartz glass 2 Recess 3 Recess group
3a Hole 4
7 Bottom
Claims (7)
少なくとも上記直胴部の内壁面の水平線上、１箇所または２箇所以上に深さが異なる窪み群からなる凹部を、前記炉の外から目視で確認したときに、いずれか１つの凹部が確認できる間隔を開けて設けたことを特徴とする減肉量が目視判定可能な石英ガラス製ルツボ。 A cylindrical straight barrel having an open edge portion on the upper surface, the bowl-shaped bottom, and a corner portion which connects them, made of quartz glass that is used by placing in a furnace pulling a silicon single crystal A crucible,
At least the horizontal line of the inner wall surface of the cylindrical body portion, a recess one place or two places or more depths of different indentations, when confirmed visually from the outside of the furnace, it can be confirmed either one recess A quartz glass crucible capable of visually judging the amount of thinning, characterized by being provided with an interval .
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